#include <bits/stdc++.h>
using namespace std;

#define int int64_t
#define endl "\n"

using PII = pair<int, int>;
using TII = tuple<int, int, int>;
template<class T> using V = vector<T>;
using i64 = long long;
using i128 = __int128;
using u64 = unsigned long long;

#define FOR(i, a, b) for (int i = (int)(a); i <= (int)(b); i++)
#define FOR2(i, a, b, c) for (int i = (int)(a); i <= (int)(b); i += c)
#define FORD(i, b, a) for (int i = (int)(a); i >= (int)(b); i--)
#define FORD2(i, b, a, c) for (int i = (int)(a); i >= (int)(b); i -= c)
#define ALL(a) a.begin(), a.end()
#define RALL(a) a.rbegin(), a.rend()
#define lowbit(x) ((x) & (-x))
#define RE return;
#define Yes cout << "Yes" << endl;
#define YES cout << "YES" << endl;
#define No cout << "No" << endl;
#define NO cout << "NO" << endl;
#define pb push_back
#define eb emplace_back
#define fi first
#define se second
#define sz(x) (int)(x).size()

void solve() {
    int n, m;
    cin >> n >> m;

    V<array<int, 3>> w(m + 1);

    FOR(i, 1, m) {
        int a, b, c;
        cin >> a >> b >> c;
        w[i] = {a, b, c};
    }

    V<int> p(n + 1, 0);

    function<int(int)> find = [&](int x) {
        if (x != p[x]) p[x] = find(p[x]);
        return p[x];
    };

    V<int> vis(m + 1, 0);

    int ans = 0;

    FORD(k, 0, 31) {
        FOR(i, 1, n) p[i] = i;
        FOR(i, 1, m) {
            if (!((w[i][2] >> k) & 1) && !vis[i]) {
                int a = w[i][0], b = w[i][1];
                a = find(a), b = find(b);
                if (a != b) {
                    p[a] = b;
                }
            }
        }
        int x = find(1);
        bool f = false;
        FOR(i, 2, n) {
            if (x != find(i)) {
                f = 1;
                break;
            }
        }
        if (!f) {
            FOR(i, 1, m) {
                if ((w[i][2] >> k) & 1) {
                    vis[i] = 1;
                }
            }

        } else {

            ans |= (1LL << k);
        }
    }

    cout << ans << endl;
}

signed main() {
    int Task = 1;

    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cin >> Task;
    while (Task--) {
        solve();
    }

    return 0;
}
